ST2202A
16. LCD CONTROLLER (LCDC)
TheꢀLCDꢀcontrollerꢀ(LCDC)ꢀprovidesꢀdisplayꢀdataꢀandꢀ
specificꢀsignalsꢀforꢀexternalꢀLCDꢀdriversꢀtoꢀdriveꢀtheꢀSTNꢀ
LCDꢀpanels.ꢀTheꢀLCDCꢀfetchesꢀdisplayꢀdataꢀdirectlyꢀfromꢀ
internalꢀsystemꢀmemoryꢀthroughꢀoneꢀuniqueꢀmemoryꢀbus.ꢀ
Theꢀspecialꢀdesignedꢀinternalꢀbusꢀsharesꢀalmostꢀnoneꢀofꢀ
theꢀCPUꢀresourcesꢀtoꢀmakeꢀbothꢀfastꢀdisplayꢀdataꢀprocessꢀ
andꢀhighꢀspeedꢀCPUꢀoperationꢀpossible.ꢀTheꢀST2202ꢀ
buildsꢀinꢀ4KꢀbytesꢀSRAM,ꢀsoꢀtheꢀmaximumꢀpanelꢀsizeꢀcanꢀ
beꢀ240x120.ꢀTheꢀLCDCꢀalsoꢀsupportsꢀsoftwareꢀgrayscaleꢀtoꢀ
richꢀtheꢀdisplayꢀinformationꢀandꢀtheꢀdiversityꢀofꢀcontentsꢀasꢀ
well.ꢀ
TheꢀST2202ꢀsupportsꢀ1ꢁꢀandꢀ4ꢁbitꢀdataꢀbusꢀforꢀtheꢀ
compatibilityꢀofꢀmostꢀpopularꢀLCDꢀdrivers.ꢀTheꢀLCDꢀoutputꢀ
signalsꢀareꢀsharedꢀwithꢀPortꢁL.,ꢀandꢀareꢀcontrolledꢀbyꢀLCDꢀ
powerꢀcontrolꢀbitꢀLPWRꢀ(LCTL[7])ꢀandꢀdataꢀbusꢀselectionꢀ
bitꢀLMODꢀ(LCK[4]).ꢀInꢀcaseꢀofꢀ1ꢁbitꢀmode,ꢀPL3~1ꢀofꢀPortꢁLꢀ
canꢀstillꢀbeꢀusedꢀforꢀgeneralꢀpurpose.ꢀ ꢀ
ꢀ
Note:ꢀTheꢀLCDꢀsignalsꢀwillꢀbeꢀdisconnectedꢀandꢀ
PortꢁLꢀwillꢀoutputꢀvaluesꢀassignedꢀbyꢀPL
afterꢀclearingꢀLPWR.ꢀ
ꢀ
ꢀ
ꢀ
Variousꢀfunctionsꢀareꢀalsoꢀsupportedꢀtoꢀrichꢀtheꢀdisplayꢀ
information,ꢀincludingꢀvirtualꢀscreen,ꢀpanning,ꢀscrolling,ꢀ
contrastꢀcontrolꢀandꢀanꢀalternatingꢀsignalꢀgenerator.ꢀControlꢀ
registersꢀusedꢀbyꢀLCDCꢀareꢀlistedꢀbelow.ꢀ
LCDCKꢀisꢀforꢀLCDCꢀtoꢀgenerateꢀtimingsꢀandꢀtheꢀpixelꢀclock.ꢀ ꢀ
ReferꢀtoꢀTABLEꢀ11ꢁ3ꢀforꢀfrequencyꢀsettingsꢀofꢀLCDCK.ꢀ
ꢀ
ꢀ
TABLE 16-1 Summary Of LCD Control Registers
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2
SSA[7]ꢀ SSA[6]ꢀ SSA[5]ꢀ SSA[4]ꢀ SSA[3]ꢀ SSA[2]ꢀ SSA[1]ꢀ SSA[0]ꢀ 0000ꢀ0000ꢀ
Address Name
R/W
Bit 1
Bit 0
Default
$040 LSSAL
$041 LSSAH
$042 LVPW
$043 LXMAX
$044 LYMAX
$045 LPAN
$047 LCTR
$048 LCK
$049 LFRA
$04A LAC
$04B LPWM
$04C PL
Wꢀ
Wꢀ SSA[15]ꢀ SSA[14]ꢀ SSA[13]ꢀ SSA[12]ꢀ SSA[11]ꢀ SSA[10]ꢀ SSA[9]ꢀ SSA[8]ꢀ 0000ꢀ0000ꢀ
Wꢀ
VP[7]ꢀ
R/Wꢀ XM[7]ꢀ
R/Wꢀ YM[7]ꢀ
VP[6]ꢀ
XM[6]ꢀ
YM[6]ꢀ
ꢁꢀ
VP[5]ꢀ
XM[5]ꢀ
YM[5]ꢀ
ꢁꢀ
REVꢀ
ꢁꢀ
VP[4]ꢀ
XM[4]ꢀ
YM[4]ꢀ
ꢁꢀ
VP[3]ꢀ
XM[3]ꢀ
YM[3]ꢀ
ꢁꢀ
VP[2]ꢀ
XM[2]ꢀ
YM[2]ꢀ
VP[1]ꢀ
XM[1]ꢀ
YM[1]ꢀ
VP[0]ꢀ
XM[0]ꢀ
YM[0]ꢀ
0000ꢀ0000ꢀ
0000ꢀ0000ꢀ
0000ꢀ0000ꢀ
R/Wꢀ
ꢁꢀ
PAN[2]ꢀ PAN[1]ꢀ PAN[0]ꢀ ꢁꢀꢁꢀꢁꢀꢁꢀꢁ000ꢀ
ꢁꢀ ꢁꢀ ꢁꢀ 100ꢁꢀꢁꢀꢁꢀꢁꢀꢁꢀ
R/Wꢀ LPWRꢀ BLNKꢀ
ꢁꢀ
ꢁꢀ
Wꢀ
Wꢀ
R/Wꢀ
R/Wꢀ
R/Wꢀ
Wꢀ
ꢁꢀ
ꢁꢀ
LMODꢀ LCK[3]ꢀ LCK[2]ꢀ LCK[1]ꢀ LCK[0]ꢀ ꢁꢀꢁꢀꢁ0ꢀ0000ꢀ
ꢁꢀ
ꢁꢀ
ꢁꢀ
ꢁꢀ
ꢁꢀ
ꢁꢀ
FRA[5]ꢀ FRA[4]ꢀ FRA[3]ꢀ FRA[2]ꢀ FRA[1]ꢀ FRA[0]ꢀ ꢁꢀꢁꢀ00ꢀ0000ꢀ
ꢁꢀ AC[4]ꢀ AC[3]ꢀ AC[2]ꢀ AC[1]ꢀ AC[0]ꢀ ꢁꢀꢁꢀꢁ0ꢀ0000ꢀ
LPWM[5]ꢀLPWM[4]ꢀLPWM[3]ꢀLPWM[2]ꢀLPWM[1]ꢀLPWM[0]ꢀ ꢁꢀꢁꢀ00ꢀ0000ꢀ
PL[5]ꢀ PL[4]ꢀ PL[3]ꢀ PL[2]ꢀ PL[1]ꢀ PL[0]ꢀ 1111ꢀ1111ꢀ
PL[7]ꢀ
PL[6]ꢀ
$04E PCL
PCL[7]ꢀ PCL[6]ꢀ PCL[5]ꢀ PCL[4]ꢀ PCL[3]ꢀ PCL[2]ꢀ PCL[1]ꢀ PCL[0]ꢀ 0000ꢀ0000ꢀ
ꢀ
ꢀ
16.1 LCD Specific Signals
TheꢀfollowingꢀsignalsꢀareꢀgeneratedꢀbyꢀLCDCꢀtoꢀconnectꢀ
toggleꢀforꢀaꢀperiodꢀofꢀ1ꢀtoꢀ31ꢀlinesꢀorꢀoneꢀframe.ꢀSeeꢀ
theꢀST2202ꢀandꢀanꢀLCDꢀpanel.ꢀTwoꢀofꢀthemꢀareꢀdedicatedꢀ
outputꢀpins,ꢀwhileꢀtheꢀrestꢀeightꢀpinsꢀareꢀmultiplexedꢀwithꢀ
sectionꢀ16.4.7ꢀforꢀregisterꢀsettings.ꢀ
ꢀ
PortꢁL.ꢀ
ꢀ
ꢀ
CP (PL4)
TheꢀLCDꢀshiftꢀclockꢀpulseꢀsignalꢀisꢀtheꢀclockꢀoutputꢀtoꢀwhichꢀ
theꢀoutputꢀdataꢀtoꢀtheꢀLCDꢀpanelꢀisꢀsynchronized.ꢀDataꢀforꢀ
segmentꢀdriversꢀisꢀshiftedꢀintoꢀtheꢀinternalꢀlineꢀbufferꢀatꢀ
eachꢀfallingꢀedgeꢀofꢀCP.ꢀ
ꢀ
ꢀ
TheꢀLCDꢀdataꢀbusꢀlinesꢀtransferꢀpixelꢀdataꢀtoꢀtheꢀLCDꢀpanelꢀ
soꢀthatꢀitꢀcanꢀbeꢀdisplayed.ꢀTwoꢀkindsꢀofꢀdataꢀbusses,ꢀ1ꢁꢀ
andꢀ4ꢁbit,ꢀareꢀsupportedꢀandꢀareꢀcontrolledꢀbyꢀLMOD
ꢀ
FLM (PL7)
TheꢀLCDꢀframeꢀmarkerꢀsignalꢀindicatesꢀtheꢀstartꢀofꢀaꢀnewꢀ
displayꢀframe.ꢀFLMꢀbecomesꢀactiveꢀafterꢀtheꢀlastꢀlineꢀpulseꢀ
ofꢀtheꢀframeꢀandꢀremainsꢀactiveꢀuntilꢀtheꢀnextꢀlineꢀpulse,ꢀatꢀ
whichꢀpointꢀitꢀdeꢁassertsꢀandꢀremainsꢀinactiveꢀuntilꢀtheꢀnextꢀ
frame.ꢀ
LD3~0 (PL3~0)
ꢀ
ꢀ
LOAD (PL6)
ꢀ
TheꢀLCDꢀlineꢀpulseꢀsignalꢀisꢀusedꢀtoꢀlatchꢀaꢀlineꢀofꢀshiftedꢀ
dataꢀtoꢀtheꢀsegmentꢀdrivers’ꢀoutputsꢀandꢀisꢀalsoꢀusedꢀtoꢀ
shiftꢀtheꢀlineꢀenableꢀsignalꢀofꢀcommonꢀdriver.ꢀAllꢀtheꢀdriverꢀ
outputsꢀthenꢀcontrolꢀtheꢀliquidꢀcrystalꢀtoꢀformꢀtheꢀdesiredꢀ
frameꢀonꢀpanel.ꢀ
(
LCK[4]).ꢀInꢀcaseꢀofꢀ1ꢁbitꢀmode,ꢀLMODꢀshouldꢀbeꢀclearedꢀ
andꢀtheꢀLCDCꢀusesꢀonlyꢀLD0ꢀtoꢀtransferꢀdata.ꢀLD3~1ꢀcanꢀ
stillꢀbeꢀprogrammedꢀtoꢀbeꢀnormalꢀinputsꢀorꢀoutputs.ꢀTheꢀ
outputꢀpixelꢀdataꢀcanꢀbeꢀinvertedꢀthroughꢀprogramming.ꢀ
SettingꢀREVꢀ(LCTR)ꢀwillꢀreverseꢀtheꢀoutputꢀdataꢀonꢀdataꢀ
bus.ꢀ
ꢀ
ꢀ
ꢀ
AC (PL5)
TheꢀLCDꢀalternateꢀsignalꢀtogglesꢀtheꢀpolarityꢀofꢀliquidꢀ
crystalꢀonꢀtheꢀpanel.ꢀThisꢀsignalꢀcanꢀbeꢀprogrammedꢀtoꢀ
ꢀ
ꢀ (Power control)
POFF
TheꢀLCDꢀpowerꢀcontrolꢀsignalꢀisꢀusedꢀtoꢀturnꢀon/offꢀtheꢀ
Verꢀ2.5ꢀ
41
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ꢀ
9/16/2008ꢀ
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